Display screen or portion thereof with an icon



FIG. 1 is a front view of a display screen or portion thereof with an icon showing my new design; and,

FIG. 2 is an enlarged view of the icon of FIG. 1.

The broken lines in FIG. 1 illustrate a display screen or portion thereof and form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with an icon, as shown and described. 